Figure 6
From: Air-coupled ultrasound detection using capillary-based optical ring resonators
(a) Schematic of the PA detection setup. A 6 ns pulsed laser at 532 nm was impinged onto a 200 nm thick Cr film deposited on a silica wafer (see Inset) to generate PA signal. (b) Temporal air-coupled PA signal detected by a ring resonator (a = 80 μm, t = 11 μm). The data were averaged 64 times. Inset: The “ringing” response can be seen after the initial peak signal. (c) Frequency response of the ring resonator towards PA signal. Frequency dependent absorption in air has been taken into account. A strong peak at 1.65 MHz and small side peaks were visible.
